Simplex 1050 image unsteady focus pulsing

[Mark Gulbrandsen]

I've had the nut that locks the gate depth setting screw that's on the trap come lose a couple times. Note that really old machines may not have that depth adjustment screw. Anyway, then it's free to travel in or out at will from vibrations if the gate is open. Also, the intermittent shaft should not have a lot of end play. I used to set them for oil clearance times about two. And check the centering of the gate shoe. It's also adjustable laterally to some degree. I've seen a side of sprocket teeth shaved off a number of times...

[Brad Miller]

Beware, do not adjust the gate closure solely on how it aligns with the intermittent shoe. Those intermittent shoes on the Simplex gates are VERY easily bent. It only take someone setting it down a bit too hard (or dropping it) during cleaning to bend it, and then you have excessive pressure at the intermittent sprocket and so forth.

[Steve Guttag]

Not to mention...that shoe is on upside down. The pointy part of the radius of the shoe should be on the exiting side (lower side). The gate should close such that the runners are about ⅛" from the aperture plate but in no way should make contact with the lower tension band support bracket (it would pinch the film, then). The shoe tang should then be adjusted for just contacting the sprocket, without film (and centered). In later gate assemblies they even made the shoe/tang a separate piece that could be adjusted after the gate clearance was set. In the vast majority, however, one has to manually bend the tang to set it and that can even include the radius of it for a good fit to the sprocket.

Note too, it is possible for the shoe to be assembled out of square. If the shoe is removed and set on a flat surface, it shouldn't rock at all. If it does, loosen the four slotted screws, press down on the shoe and retighten so that it doesn't rock.

If the shoe has been grooved from misalignment, it needs to be sanded down or that groove will cut into the film and cause shedding if not other damage. Ideally, the worn parts are replaced so that they can wear in correctly.

[Kirk Futrell]

Not to mention...that shoe is on upside down. The pointy part of the radius of the shoe should be on the exiting side (lower side). The gate should close such that the runners are about ⅛" from the aperture plate but in no way should make contact with the lower tension band support bracket (it would pinch the film, then). The shoe tang should then be adjusted for just contacting the sprocket, without film (and centered). In later gate assemblies they even made the shoe/tang a separate piece that could be adjusted after the gate clearance was set. In the vast majority, however, one has to manually bend the tang to set it and that can even include the radius of it for a good fit to the sprocket.

Note too, it is possible for the shoe to be assembled out of square. If the shoe is removed and set on a flat surface, it shouldn't rock at all. If it does, loosen the four slotted screws, press down on the shoe and retighten so that it doesn't rock.

If the shoe has been grooved from misalignment, it needs to be sanded down or that groove will cut into the film and cause shedding if not other damage. Ideally, the worn parts are replaced so that they can wear in correctly.

This is all great stuff. I set the gate to close to a tiny bit less than an 1/8" so that it doesn't pinch at the bottom and the shoe just barely touches. When I took off the original shoe, I discovered it was grooved as you had guessed. I happened to have an older Simplex X-L (I think) as a parts projector and its shoe assembly seemed to be in good shape so I squared it up and put that on (the right way round this time....).
I still plan on putting the original intermittent back in but that will have to wait until Monday now.

[Steve Guttag]

Depending on the heat on the gate, a closer spacing may or may not cause an issue (the film swells towards the aperture plate. On the upside, the closer the spacing, the less of an aperture shadow you'll have.

[Kirk Futrell]

I seem to have gotten it ironed out. I think there were multiple issues. The gate depth, the upside down shoe (embarrassing), and the one I am most embarrassed to finally realize, was that the turret focus plane adjustment (little white plastic screws) were not all engaged. I had messed with them recently and found the best overall focus was with only two of the three engaged. I redid the focus making sure they all were tight and that got rid of the remainder of the issue.
Gate depth cleared up jitter and focus plane adjustment cleared up bouncing focus.
I appreciate everyone's time and suggestions for the past 20 something years I have been finding answers here.

This is sort just for fun, but here is an image of both projectors running the same format of test film (I only have one rp40 sadly) they are at a considerable offset with the digital projector in-between but the center horizontal and vertical lines now are steady with each other. Ignore the light focus its just my phone camera shutter rate issue. There is only a tiny bit of instability at the extreme top and bottom. This is miles better!



overlap.jpg

[Mark Gulbrandsen]

Awesome! You have quite the line up this weekend, so we may head there and see something...